Conventionally, transparent resin materials such as silicone resin and epoxy resin have been widely used as materials (sealing materials) for sealing electronics components such as a semiconductor light-emitting element. However, there is a concern about these resin materials. That is to say, these resin materials have low resistance against moisture and heat. Also, another problem is that, when any of the resin materials is used as a package material for packaging a light-emitting element, the resin deteriorates over time by the ultraviolet emitted by the light-emitting element, and the light transmittance is reduced. Furthermore, although a material having a high transmittance is strongly desired as a package material for packaging a light-emitting element so as to realize high light extraction efficiency, many resin materials have a refractive index of approximately 1.5 at the highest, and thus a further improvement is expected. Note that in the present document, the semiconductor light-emitting element may be referred to simply as “light-emitting element” or “element”.
Under such backgrounds, glass compositions have been considered as package materials for packaging light-emitting materials in recent years, from the viewpoints of the moisture resistance, heat resistance and high transmittance. For example, a P2O5—ZnO—SnO-based glass composition, whose major components are P2O5, ZnO and SnO, has been proposed (see, for example, Patent Literatures 1 and 2).